Brain deterioration, sleep woes linked

MEMORY

Updated 7:44 pm, Tuesday, February 5, 2013

Photo: Jessica Olthof, The Chronicle

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Bryce Mander showing off electrodes in Tolman Hall on February 2nd, 2013 in Berkeley, Calif. Bryce Mander, a postdoctoral fellow at UC Berkeley, recently published a study linking brain atrophy in older people to trouble getting deep sleep to memory problems. He does research on the connections between sleep and the brain. less

Bryce Mander showing off electrodes in Tolman Hall on February 2nd, 2013 in Berkeley, Calif. Bryce Mander, a postdoctoral fellow at UC Berkeley, recently published a study linking brain atrophy in older people ... more

Photo: Jessica Olthof, The Chronicle

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Postdoctoral fellow Bryce Mander takes a close look at some of the electrodes used in his research.

Postdoctoral fellow Bryce Mander takes a close look at some of the electrodes used in his research.

Photo: Jessica Olthof, The Chronicle

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Bryce Mander, a postdoctoral fellow at UC Berkeley, plugs in electrodes in a sleeping room in Tolman Hall. Below: The electrodes are used to help measure participants' brain waves as they sleep.

Bryce Mander, a postdoctoral fellow at UC Berkeley, plugs in electrodes in a sleeping room in Tolman Hall. Below: The electrodes are used to help measure participants' brain waves as they sleep.

Photo: Jessica Olthof, The Chronicle

Brain deterioration, sleep woes linked

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Hallmarks of aging include brain atrophy, a decline in sleep quality and memory problems, and new research from UC Berkeley has uncovered a relationship among them.

After comparing the brains and memory skills of young study participants and older subjects, researchers found that age-related brain deterioration contributes to poor sleep and, in turn, recollection problems.

"We were surprised by how clear that was," said Bryce Mander, a postdoctoral fellow in the psychology department and the lead author of the recent study, published last month in the journal Nature Neuroscience.

If scientists can discover ways to enhance sleep in older people - the type of deep sleep that produces what are known as slow waves - then it is possible to make strides in improving memory, the research suggests.

The Berkeley researchers examined 18 adults, with an average age of about 20, and 15 other adults with an average age of 72. Before going to bed one night, the subjects had to try to memorize 120 word pairs consisting of one familiar word like "crook" and a nonsense word like "engarleys" to make it harder to recall.

As the participants slept, researchers measured their brain waves, and the next morning, the subjects were tested on the word pairings. The older subjects did not fare as well as their younger counterparts.

"When they came back the next day, they had forgotten about 55 percent more than the young adults," said Matthew Walker, a UC Berkeley professor of psychology and neuroscience.

Sleep and memory

Long-term-memory storage depends on the slow waves generated by deep sleep, and researchers found that the older adults got about 75 percent less deep sleep than the young adults.

Walker likened the waves to a chairlift that picks up new memories from the hippocampus - which can hold memories only temporarily - and escorts them to the prefrontal cortex, where they are cemented into the brain's architecture. Brain scans during the morning test showed that the younger participants were relying on the cortex to recall the word pairs while the older people were still counting on the hippocampus.

What was causing the sleeping troubles - and thus the memory problems - was the natural atrophy of the aging brain, researchers found.

Past research has established that the frontal lobe atrophies as people age, and that portions of the region contribute to sleep. But the Berkeley researchers were able to determine the amount of brain atrophy correlated to the reduction in sleep quality, which in turn corresponded to how many word pairs a person was able to remember.

"It's not just that they're associated with each other," Walker said. "We can understand the directionality of what's happening and figure out the chain of command."

Potentially treatable

The findings go beyond explaining why older people have more trouble remembering where they stashed their keys the night before. Although sleep is just one factor in age-related memory issues, it is a potentially treatable problem - "a silver lining to rather depressing news," Walker said.

Past studies in young people have found that electrical stimulation during sleep can enhance slow waves and improve memory, Walker said, and there are plans to do similar research in older subjects.

There is also a possible connection to neurodegenerative disorders, which are associated with greater brain atrophy and more disrupted sleep.

"Is the same pathway even more dysfunctional in conditions such as Alzheimer's?" Walker said.

The recent UC Berkeley study was just one of many sleep-related projects going on in the Bay Area, a hub for sleep research. Stanford has a number of centers focused on studying sleep, sleep disorders and their health impacts.

One project researchers at Stanford are working on is looking at whether a popular treatment for sleep apnea can improve neurocognitive function in patients. Sleep apnea has been shown to impact attention, learning and memory, and executive and frontal lobe function, said Dr. Clete Kushida, the medical director of the Stanford Sleep Medicine Center and the director of the Stanford Center for Human Sleep Research.

Sleep and emotions

UC Berkeley researchers are also examining the connection between sleep and emotional regulation. Walker's past work has found that sleep deprivation can trigger a greater activation of the amygdala, which is responsible for emotional responses. A lack of sleep simultaneously quiets the prefrontal cortex, which helps a person calm down.

"It's like a car with an accelerator and no brakes," said Allison Harvey, a professor of psychology at UC Berkeley. "We all know this - under conditions of sleep deprivation, we're an emotional wreck the next day."

One study showed sleep-deprived people reacted more emotionally when shown upsetting images, but once they caught up on sleep, the experience was not as painful for them.

Harvey, who is also the director of the Golden Bear Sleep and Mood Research Clinic at UC Berkeley, has tried to turn those findings into interventions for patients with trouble regulating emotions.

Harvey and other researchers have found that improved sleep has helped people with bipolar disorder - which is marked by sleeping problems in addition to emotional control issues - reduce their bouts of mania and depression.

"It's one of those situations where brain and behavior are really intimately linked," Harvey said.

The therapy relies on sessions with a sleep coach who tries to help patients change their sleeping habits. The treatment also includes a list of recommended steps that people should do to improve their sleep, from establishing a bedtime routine to avoiding nightcaps, and researchers have found that people adhere to them better when they have a coach to keep them accountable.

Harvey is now working to see if improved sleep can help another group known for emotional regulation troubles - teenagers.

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